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Extracellular ATP plays a role in nociceptive signalling and sensory regulation of visceral function through ionotropic receptors variably composed of P2X₂ and P2X₃ subunits. P2X₂ and P2X₃ subunits can form homomultimeric P2X₂, homomultimeric P2X₃, or heteromultimeric P2X_2/3 receptors. However, the relative contribution of these receptor subtypes to afferent functions of ATP in vivo is poorly understood. Here we describe null mutant mice lacking the P2X₂ receptor subunit (P2X₂^−/−) and double mutant mice lacking both P2X₂ and P2X₃ subunits (P2X₂/P2X₃^Dbl−/−), and compare these with previously characterized P2X₃^−/− mice. In patch‐clamp studies, nodose, coeliac and superior cervical ganglia (SCG) neurones from wild‐type mice responded to ATP with sustained inward currents, while dorsal root ganglia (DRG) neurones gave predominantly transient currents. Sensory neurones from P2X₂^−/− mice …